Original paper

Cellulase activity in anaerobic degradation of aquatic macrophytes tissues

Zauner Gimenes, Karen; Bianchessi da Cunha-Santino, Marcela; Bianchini, Irineu

Abstract

Macrophytes are responsible for a large input of detrital organic matter in tropical lentic aquatic systems, thus this study aimed to evaluate the different aspects involved in anaerobic decomposition (i.e.cellulase activity, leaching and mineralization) of Cyperus giganteus, Eichhornia azurea and Egeria najas. Decomposition chambers comprising macrophyte detritus and lagoon water were set up and incubated at 17.4 and 27.8 °C in the dark. In each sampling day, the mass of the detritus particulate fraction, the cellulose content and the cellulolytic activity were evaluated. The detritus presented a labile and/or soluble (POMLS) and a refractory (POMR) fraction. Based on the decomposition kinetics, the leaching process was faster than the degradation of refractory compounds. C. giganteus detritus presented the highest contents of POMR and longer half-life times, and the higher cellulose content. The cellulose degradation was higher for E. najas regardless of temperature incubation, although the highest accumulated cellulolytic activity was observed in the degradation of E. azurea. In conclusion: (i) temperature affected the leaching coefficient but did not alter the decay velocity of POMR; (ii) regardless of temperature, the POMR contents and the decomposition times were shorter for E. najas and higher for C. giganteus and (iii) higher temperature increased the cellulase activity in C. giganteus and E. najas tissues, but a reduced activity was observed during degradation of E. azurea, indicating that temperature displays a different pattern depending on macrophyte life form.

Keywords

cyperus giganteuseichhornia azureaegeria najascelluloseanaerobiosetemperature